In general, rotary impact tools, such as impact wrenches, are power tools that drive socket accessories to apply torque to lug nuts, bolt heads, and similar types of fasteners. These tools typically comprise a housing that encloses a motor, an impact mechanism, and an anvil. The anvil is rotatably supported in the housing. The motor drives the impact mechanism to deliver repeated impacts to the anvil which causes the anvil to rotate. The anvil includes an external drive surface that is received in the bore of a socket accessory tool. The drive surface and the bore typically have complementary polygonal shapes that enable the socket accessory tool to be driven to rotate with the anvil.
Impact tools are equipped with an accessory retention device for releasably retaining socket accessory tools to the external drive surface of the anvil. Spring-loaded ball detents are one example of a retention device known in the art. The ball detent protrudes from a detent bore defined in the drive portion of the anvil. When a socket accessory tool is installed on the drive portion of the anvil, the ball detent protrudes into a recess defined in the socket accessory tool to hold the socket accessory tool in place. The socket accessory tool compresses the ball detent into the detent bore during installation and removal. Therefore, ball detent retention devices typically do not require deliberate action by the user of the impact tool to install or remove a socket accessory tool.
In certain circumstances, however, it is important that the socket accessory tool be fully secured onto the tool such that it cannot be removed without a deliberate action by the user. In these cases, a pin detent retention device is often used. Similar to the ball detent, the pin detent is positioned in a detent bore defined in the drive portion of the anvil and protrudes from the detent bore into a complementarily positioned through-hole, or passage, defined in a socket accessory tool. The pin detent provides a positive stop or barrier that prevents the removal of the socket accessory tool. Pin detent retention devices typically require the use of a tool, such as a thin rod or pin, to enable the removal the socket accessory tool. The pin or rod is inserted into the passage and is used to press the pin detent down into the bore so the socket accessory tool can be removed.
Previously known pin detent retention devices, however, require deliberate action by the user to press the pin detent into the bore to enable installation of a socket accessory tool as well. In some cases, socket accessory tools may bottom out on the pin detent when installed on the anvil thereby subjecting the pin detent to shear loading. Shear loading can shorten the useful life of the pin detent.
What is needed is a retention device for releasably securing a socket accessory tool to the anvil of an impact tool that allows socket accessory tools to be easily installed while still requiring deliberate action by the user to remove the socket accessory tool. Also, what is needed is a socket retention device that can accommodate different socket designs without being susceptible to the damaging effects of shear load on the retention device from the sockets themselves.